kokoro: Various fixes to merge-into-chromeos job

- Adds the needed job config
- Makes a copy of the script before git checkout
- Follow naming scheme of other build scripts
- Add reviewer when uploading

BUG=b:209034086
TEST=./ci/kokoro/simulate build-merge-into-chromeos.sh

Change-Id: I279ff6aca7c3c304354a238ebd5c40b4dd272385
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3321726
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: Dennis Kempin <denniskempin@google.com>

ci/kokoro/build-merge-into-chromeos.sh

@@ -34,11 +34,15 @@ gerrit_prerequisites() {
 }
 
 upload() {
+    git push origin HEAD:refs/for/chromeos%r=crosvm-uprev@google.com
+}
+
+upload_with_retries() {
     # Try uploading to gerrit. Retry due to errors on first upload.
     # See: b/209031134
     for i in $(seq 1 $RETRIES); do
         echo "Push attempt $i"
-        if git push origin HEAD:refs/for/chromeos; then
+        if upload; then
             return 0
         fi
     done
@@ -49,11 +53,15 @@ main() {
     set -e
     gerrit_prerequisites
 
-    # Perform merge on a tracking branch.
-    git checkout -b chromeos
-    git branch --set-upstream-to origin/chromeos chromeos
-    ./tools/chromeos/create_merge
+    # Make a copy of the merge script, so we are using the HEAD version to
+    # create the merge.
+    cp ./tools/chromeos/create_merge "${KOKORO_ARTIFACTS_DIR}/create_merge"
 
-    upload
+    # Perform merge on a tracking branch.
+    git checkout -b chromeos origin/chromeos
+    git branch --set-upstream-to origin/chromeos chromeos
+    "${KOKORO_ARTIFACTS_DIR}/create_merge"
+
+    upload_with_retries
 }
 main

ci/kokoro/merge-into-chromeos.cfg

@@ -0,0 +1,3 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+build_file: "crosvm/ci/kokoro/build-merge-into-chromeos.sh"

tools/chromeos/create_merge

@@ -15,7 +15,6 @@
 # To merge with a specific commit, use: ./tools/chromeos/create_merge $SHA
 
 set -e
-cd "$(dirname "${BASH_SOURCE[0]}")/../../" || exit
 
 LOCAL_BRANCH=$(git branch --show-current)
 REMOTE_NAME=$(git config "branch.${LOCAL_BRANCH}.remote")